Batteries, coupling and backup

How much energy, how much power?

kWh describes stored energy; kW describes delivery power. An 8 kWh battery is not automatically able to run an 8 kW load. Usable reserve, conversion losses, output limits and motor start-up demands affect what can run and for how long.

A battery can move surplus solar into the evening. It does not create energy. A reserved outage buffer leaves less energy available for daily bill savings.

AC-coupled versus DC-coupled

Do not assume any battery can be attached to any inverter. Confirm manufacturer-approved combinations, operating modes and the approved interconnection.

Charging from Meralco before an outage

Some compatible battery systems allow scheduled grid charging or a higher backup reserve. Your installer must confirm that the supplied equipment, firmware, tariff and utility arrangement permit it. Charging buys electricity and incurs losses; it is not free solar energy.

For example, at 90% round-trip efficiency, delivering 8 kWh requires about 8.89 kWh of charging energy. Off-peak charging only saves money if the avoided later purchase outweighs charging cost, losses and battery wear. Confirm that grid-charged energy is not exported contrary to your agreement.

Backup: safe isolation and a supported power source

A correctly designed backup-capable system can safely isolate your home from Meralco and establish a local electrical supply for supported loads, using compatible controls and an available power source. Grid-following solar ordinarily shuts down when the grid fails.

Atmoce MU100-S and MU100-T are backup equipment for their supported electrical configurations. Backup hardware and battery storage are separate selections. The backup unit does not store energy; battery-free outage operation needs manufacturer confirmation of the complete system, its operating mode and available power source.

Your installer confirms whether the design serves essential circuits or the whole home, including running and starting power. Ask for demonstrated changeover and expected runtime under a stated load. Solar availability varies with daylight and weather.

Separate resilience from payback

Batteries add cost and age through time and use. Their warranty may be shorter than a panel performance warranty and may include cycle, throughput and retained-capacity conditions. Compare actual warranties rather than assuming a universal duration.

Net metering may monetize surplus without buying storage, but does not provide outage power. The comparison tool models solar charging only and excludes time-of-use arbitrage and replacement costs; it is not a battery lifetime forecast.